This research program combines biomedical engineering efforts at Riverside Research Institute (RRI) and biological and medical investigations at Cornell University Medical College (CUMC) to improve the treatment of ocular tumors and help to assess the safety of diagnostic ultrasound techniques being applied to ophthalmology. To achieve these goals, the proposed research addresses a number of fundamental phenomena involved in the propagation of intense ultrasound and its interaction with tissue structures. Therapy applications involve the development of intense, short-term ultrasound exposures to treat substantial tumor volumes before-flow cooling and attendant uncertainties become significant. Special ultrasound ablation techniques involve adaptable beams to produce immediate changes in resistant tumor regions. A comprehensive computer simulation provides a model of relevant beam propagation and tissue heating. In-vivo ultrasonic tissue characterization techniques and 3-D scanning are used together with histopathology and biologic assay to characterize induced therapeutic changes. In-vitro, in-vivo, and clinical procedures are conducted to improve the technique and to verify model predictions. Safety studies involve ultrasonic pulsed Doppler exposures of the eye, with particular attention to the potential for thermal damage in the absorptive, avascular ocular lens. Very-high-resolution (VHR) ultrasound systems, which can resolve fine-scale microstructure (e.g., 30-micro m dimensions), are also under study; these systems apply frequencies (e.g., 50 MHz and above) that are much higher than those previously used in biological-effects experiments. They safety studies are intended to identify procedures and design criteria needed to support the continued development and safe use of modern ultrasonic capabilities. While these investigations involve practical needs in ophthalmology, they provide fundamental information regarding non-invasive tumor therapy and diagnostic safety for a broad spectrum of medical applications.